Our Animals > Sei Whale
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The Sei Whale (Balaenoptera borealis) (Sei is pronounced "say")

Fun Facts

• The Sei sperm whale is a federally endangered species.
• They can grow as long as 50 feet.
• They can weight up to 40 tons.
• They are the third largest baleen whale.
• They are dark grey, with white variations on their belly.
• They have 320 to 380 Baleen plates that are about 19 inches long each for feeding.
• They are quite possibly the fastest whale being able to cruise at 16 mph with a maximum speed of 40 mph.
• From December to April they eat very little or fast, living off of their built up fat reserves.
• In autumn, they migrate several thousand miles to equatorial waters where it is warmer.

Distribution

They live in the North Atlantic Ocean ranging from Iceland south to the northeastern Venezuelan coast, and northwest to the Gulf of Mexico . There are also records from Cuba and the Virgin Islands. Sei whales are seen infrequently in U. S. waters.

Food

Like other baleen whales, Sei whales are filter feeders.  Sei whales eat copepods, krill, squid and small schooling fish.

Social Structure

Little is known about the actual social system of these animals. Groups of two to five individuals are typically observed, but sometimes thousands may gather if food is abundant. However, these large aggregations may not be dependent on food supply alone, as they often occur during times of migration. Norwegian workers call the times of great Sei whale abundance "invasion years." During mating season, males and females may form a social unit, but strong data on this issue are lacking.

Sound Production

Surprisingly, no conclusive recordings of this species have ever been reported, with the exception of one encounter.